Crossheads have long been used in motors, pumps, compressors and other machines to smoothly convert rotational motion into linear motion. As is well known, conventional crossheads slide linearly between a pair of cupped guides at their tops and bottoms. These guides have always been difficult to lubricate and have tended to wear unevenly, imparting a wobbling motion to a crosshead as it moves. Unfortunately, in cases where a crosshead is connected to a piston as in a pump, crosshead wobble has been found to break down the packing surrounding the piston and cause the pump to leak. Leaks of this sort often require costly and time-consuming repairs made worse by the lost value of the broken machine's output during the repair period.